Traditionally, a hernia bulging through any region of the abdominal wall would be repaired by an open hernioplasty and based on a method where the hernia defect becomes closed and reinforced by adjacent tissues. In cases of very large or recurrent hernias, meshes of some nonabsorbable synthetic material have been used for repair. During a period of 3 to 6 months following the hernia operation, the repaired site gradually gathers scar tissue which builds up to strengthen the region.
Recurrent hernias are a common problem in hernia surgery. Even the best reports indicate from 1% to 4% recurrent hernias after primary surgery, and some authors report figures up to 20%. These figures are much lower when a non-absorbable mesh is utilized in the method of repair.
The new trends for hernia repair include mini-invasive techniques, in which the hernia defect is closed by a piece of non-absorbable mesh with minimal tension. The follow-up times thus far are short for such procedures, but it seems that recurrence rates of 1% or below could be expected. Also, the general recovery time has become shorter, and the patients are usually encouraged to begin their normal activities with no restrictions within a week after the operation.
The commercially available meshes used in hernia repair today are typically made of various plastics. They are known to stay biostable and safe at least for the usual follow-up time of 5 to 10 years after implantation. However, many hernia patients are young people with expected lifespans of decades. Nothing is known about the fate of, or tissue reactions possibly awakened by, the relatively massive plastic meshes after implantation and passage of some decades. Permanent surgical implants (metals, plastics, silicone, etc.) have been shown to cause side effects in many patients because of corrosion, wearing, migration, chronic inflammation and risk of infection. When the foreign material is placed near sensitive organs, the risks of these side effects can be severe to the patient's well being. In the case of hernia surgery, the plastic mesh will always become situated into close contact with the sensitive intra-abdominal organs.
Bioabsorbable meshes made of polyglycolic acid and its lactide copolymer (e.g., DEXON.TM., available from Davis & Geck, USA; and VICRYL.TM., available from Ethicon, Johnson & Johnson, U.S.A., are also known. Since the 1970's, these same materials have been used in surgery as sutures. No major harm to the tissues has been generally reported from use of these materials, and these materials also induce fibrogenesis and scar formation to some extent. Unfortunately, sutures and meshes manufactured of polyglycolic acid or its lactide copolymers (with around 10 mol-% of lactide units) tend to lose their strength within about 1 month after implantation, in which time the hernia site would not have enough time to heal and form scar tissue to resist pressure.